Aspects of the present invention relate to the monitoring and control of a substrate fabrication process.
Advances in electronic circuit technologies are requiring substrate features to have increasingly smaller or finer sizes, such as thinner interconnect lines and higher aspect ratios vias. Typically, the substrate is a semiconductor or dielectric substratum, that is processed to form features composed of dielectric, semiconducting and conducting materials, on the substrate. Small sized features allow packing of larger numbers of features into smaller areas and their operation at higher frequencies. For example, metal-containing interconnect lines are often being sized less than about 0.18 nm, and sometimes, even less than about 0.15 nm. However, it becomes increasingly difficult to fabricate such features with consistent dimensions and shapes across the substrate surface, especially as the features become ever smaller in size. In such fabrication process, unpredictable variations in process variables across the substrate surface can form features having different dimensions at different regions of the substrate surface. This makes it difficult to properly design a circuit or display, since the electrical or other properties of the features randomly vary across the substrate surface.
The problem of fabricating the fine features is all the more difficult when the features have tolerance ranges that are much smaller than those of conventional features. Variations in feature size or shape across the substrate that were previously acceptable for larger sized conventional features are longer no acceptable for the fine features. Feature shape variability is especially a problem when the critical dimensions of the features are those that vary across the substrate surface. The critical dimensions are those dimensions that significantly affect the electrical properties of the features. For example, the line width of interconnect lines is a critical dimension, because when a portion of an interconnect line is over-etched, the excessively thin portion has a higher resistance. Even a small change in dimension or sidewall taper angle of such an interconnect feature can result in out of tolerance electrical properties. As a result, many circuits having finely sized features are rejected for not meeting dimensional tolerance ranges as compared to conventional circuits.
Thus, it is desirable to be able to form finely sized features on a substrate that have consistent shapes and dimensions. It is further desirable to ensure that the features have uniform critical dimensions irrespective of their location on the substrate surface. It is also desirable to etch ultra fine features with good processing throughout and high yields.
In one aspect of the invention, a substrate processing apparatus has a process chamber having a substrate support to receive a substrate, the substrate having first and second regions, a gas distributor to introduce a gas into the chamber, a gas energizer to energize the gas to form features on the substrate, and a gas exhaust port to exhaust the gas. The apparatus also has a process monitor to monitor a dimension of a pattern of spaced apart and discrete features being formed in the first region of the substrate and generate a first signal, and monitor a dimension of a pattern of spaced apart and discrete features being formed in the second region of the substrate and generate a second signal. The apparatus further has a chamber controller to receive the first and second signals and operate the substrate support, gas distributor, gas energizer, or gas exhaust port, to set process parameters including one or more of a gas flow rate, gas pressure, gas energizing power level, and substrate temperature, to process the features in the first and second regions to compensate for any differences in the dimensions of the features being formed in the first and second regions.
A version of a method of processing a substrate includes placing a substrate in a process zone, the substrate having first and second regions, introducing a process gas into the process zone, energizing the process gas to form a pattern of spaced apart and discrete features on the substrate and exhausting the process gas. A dimension of a pattern of spaced apart and discrete features being formed in the first region of the substrate is monitored and a first signal is generated. A dimension of a pattern of spaced apart and discrete features being formed in the second region of the substrate is also monitored and a second signal is generated. The first and second signals are evaluated and process parameters in the process zone are set to process the features in the first and second regions to compensate for any differences in the dimensions of the features, the process parameters including one or more of a gas flow rate, gas pressure, gas energizing power level, and substrate temperature.
In another aspect of the invention, a substrate etching apparatus has an etching chamber having a substrate support to receive a substrate, the substrate having a central region exposed to a first processing sector of the chamber and a peripheral region exposed to a second processing sector of the chamber, a gas distributor to introduce an etching gas into the chamber, a gas energizer to energize the etching gas to etch features on the substrate, and a gas exhaust port to exhaust the etching gas. The substrate etching apparatus also has a first light detector to detect light reflected from features being etched at the central region of the substrate and generate a first signal proportional to a measured dimension of the features, and a second light detector to detect light reflected from features being etched at the peripheral region of the substrate and generate a second signal proportional to a measured dimension of the features. A chamber controller receives and evaluates the first and second signals and operates the etching chamber to set a process parameter at a controllable first level in the first processing sector, the first level being selected in relation to the first signal, and the process parameter at a controllable second level in the second processing sector, the second level being selected in relation to the second signal, thereby providing independent monitoring and control of the dimensions of the features being etched at the central and peripheral regions of the substrate.
A version of a substrate etching method includes placing a substrate in a process zone, the substrate having a central region exposed to a first processing sector of the chamber and a peripheral region exposed to a second processing sector of the chamber, introducing an etching gas into the process zone, energizing the etching gas to etch features on the substrate, and exhausting the etching gas. Light reflected from features being etched at the central region of the substrate is detected and a first signal proportional to a critical dimension of the features is generated. Light reflected from features being etched at the peripheral region of the substrate is also detected and a second signal proportional to a critical dimension of the second features is generated. The first and second signals are evaluated and the chamber is operated to set a process parameter at a controllable first level in the first processing sector, the first level being selected in relation to the first signal, and the process parameter at a controllable second level in a second processing sector, the second level being selected in relation to the second signal, thereby providing independent monitoring and control of the critical dimensions of the features at the central and peripheral regions of the substrate.
In yet another aspect, a substrate etching apparatus has a chamber having a substrate support to receive a substrate, the substrate having first and second regions, a gas distributor to introduce an etching gas into the chamber, a gas energizer to energize the etching gas to etch features in the substrate, and a gas exhaust port to exhaust the etching gas. The etching apparatus also has a first light detector to detect light reflected from features in the first region of the substrate and generate a first signal proportional to a dimension of the features, and a second light detector to detect light reflected from the second region of the substrate and generate a second signal proportional to a dimension of the features. A chamber controller evaluates the first and second signals and selects an etching process recipe in relation to the first and second signals, and operates the chamber according to the etching process recipe, whereby the etching of the features at the first and second regions is independently monitored and controlled.
Another method of etching a substrate includes placing a substrate in a process zone, the substrate having first and second regions, introducing an etching gas into the process zone, energizing the etching gas to etch features on the substrate, and exhausting the etching gas. Light reflected from features in the first region of the substrate is detected and a first signal is generated. Light reflected from features in the second region of the substrate is also detected and a second signal is generated. The first and second signals are evaluated and an etching process recipe is selected in relation to the first and second signals. Process parameters in the chamber are set according to the etching process recipe, whereby etching of the features at the first and second regions is independently monitored and controlled.